Support for embedding resources in an executable

[neonichu]

Basic support for a new .embed resource rule which will allow embedding the contents of the resource into the executable code by generating a byte array, e.g.

@_implementationOnly import struct Foundation.Data
    
struct PackageResources {
static let best_txt = Data([104,101,108,108,111,32,119,111,114,108,100,10])
}

Note that the current naïve implementaton will not work well for larger resources as it is pretty memory inefficient.

[MaxDesiatov]

Would it be better for performance if it was embedded as a [UInt8] array? That way you don't need to decode base64 at run time. You also don't need to rely on Foundation.Data then.

[neonichu]

I updated the PR, but I think we'd still want to rely on Data instead of offering just a byte array?

[abertelrud]

I updated the PR, but I think we'd still want to rely on Data instead of offering just a byte array?

Although the bundle form of this code generation does rely on Foundation, I think it makes sense for the byte array form to not do so. That makes it useful on, say, new platforms that doesn't have Foundation yet (or is having Foundation now a requirement for any new platform that claims to support Swift? — I've lost track of how core it is now considered to the Swift standard libraries).

[neonichu]

Updated naming to embedInCode and changed the generated code to bare [UInt8].

[tomerd]

cool 👍

[tomerd]

looks good. I guess its draft since we need some tests?

[neonichu]

Added a test now, so this is ready for review. Note that the test is part of FunctionalTests which is currently disabled so it won't run on CI at this time.

[neonichu]

@swift-ci please smoke test

[neonichu]

Seeing another immediate failure for Windows here, cc @shahmishal

[shahmishal]

@swift-ci test Windows

[neonichu]

@swift-ci smoke test Windows

[neonichu]

@swift-ci smoke test macOS

[tomerd]

thanks for adding this great feature @neonichu , should we add an entry in the change log / release note? seems important to communicate this one

[neonichu]

Added in #6132